Basic Guidelines For English Spellings
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See US English definition of effective
See UK English definition of effective
See Spanish definition of eficaz
1‘there is no effective treatment for this condition’
ineffective, incompetent, weak
2‘a more effective argument can be constructed in support of the opposite point of view’
weak
3‘the new law will become effective three months from now’
invalid
4‘the region did not come under effective Dutch control until 1904’
theoretical
‘no one doubts that these measures will be effective’
fail, have no effect